Method and machine for producing gears



May 22,1945. E. WILDHABER METHOD AND MAQHINEFOR PRODUCINQ GEARS I ll Sheets-Sheet 1 Filed July 9, 1941 May 22, 1945. E. \VNILDHABER 1 7 2,376,465

METHOD AND MACHINE FOR PRODUCING GEAliS Filed July 9, 1941 l 1 Sheets-Sheet 2- lnvcnfot EENES 7' WILD HA BER May I 22,

E. WILDHABER METHOD AND MACHINE FOR PRODUCING GEARS Filed July 9, 1941 11 Sheets-Sheet 5 Zhudgntop ERA/E57" W/LDHHBER (Irttorneg May 22, 1945.

E. WILDHABER METHOD AND MACHINE FOR PRODUCING GEARS Filed July 9, 1941 11 shets-sneet 4 ERNEST wan/mate v v I i Gttomeg May 22,1945. I E. WILDHABER 2,376,465

' METHOD AND MACHINE FOR PRODUCING GEARS Filed Jui 9, 1941 11 Sheets-Sheet 5 lm cntor EANEj 7' W/LDHHBER May 22, 1945. E IL E 2,376,465

METHOD AND MACHINE FOR PRODUCING GEARS Filed July 9, 1941 11 Sheets-Sheet a 3 lmcntor ERNEST W/LDHHB5R May 22, 1945. E. WILDHABER METHOD AND MACHINE FOR PRODUCING GEARS Filed July 9, 1941 11 Sheets-Sheet 7 I Zmventr ERNEST w/Lo/maE/i' B5 5 Q I v/ i (Ittomeg 7E. WILDHABER METHOD AND MACHIQE FOR PRODUCING GEARS Filed Ju1y9, 1941 EENES 7' w/z 0/1555 7 Gttom'eg 11 Shets-Sh'eet 8 Mav 22, 1945. Y 5 wlLDHABER 2,376,465 METHOD AND' MACHINE FOR PRODUCING GEARS Filed July 9, 1941 ll Sheets-Sheet 9 I N s [K g? i Q a H? k w I! 1 s g 3nvenfv fie/VEST W/LDHABf Q u k I httorneg May 22, 1945. .E. WILDHABER,

METHQD AND MACHINE FOR PRODUCING GEARS Filed July 9, 1941 l1Sheets-5heet l0 ZSnnenzfor ERNEST W/LDHA BER By T 4 Clttorneg METHOD AND MACHINE FOR PRODUCING GEARS Filed July 9, 19 11 ll Sheets-Sheet '11 ZSnuentor ER/v55 r W/L 0H4 BEE ttorne g tools.

Patented May 22,1945

,. UNITED STATES PATENT OFFICE METHOD AND ma a Foa rnonnome Ernest Wildhaber, Brighton, N. Y., assignmto Gleason Works, Rochester, N. Y., a corporation of New York Application July -9, 1941, Serial No. 401,631

' 25 Claims. (oi. 90-9) The present invention relates to a method and machine for producing gears and particularly to a. method and machine for rough-cutting straight bevel gears.

Various processes have been employed heretofore for roughing straight bevel gears.

For manufacturing work, it has been customary to use a disc milling cutter of large diameter, and

to rough each tooth slot simply by rotating this far at any point along the length of the tooth 20 space. This process is fast but it cuts tooth slots ,with concave bottoms and these tooth spaces do not taper in width from end to end, as is required in bevel gears. Moreover, at any point along .the length of the tooth space, the tooth profiles only approximate the required finished tooth shape. There is, therefore, a considerable amount of stock left on the roughed tooth spaces to be removed in the finishing operation.

For jobbing work, it is common to employ a smaller size disc milling cutter and to'rough the but unless a generating roll is employed, the tooth profiles produced are only. approximate. Moreover, the process is slow.

In my pending application, Serial No. 181,177, filed December 22, 1937, now Patent No. 2,267,181, issued December 23, 1941, I have described a method for cutting straight bevel gears with tooth spaces that taper properly in width and depth from end to end and that have straight tooth bottoms and correct tooth profile shapes, and in the pending joint application of Clarence T. Galloway and myself, Serial No. 215,188, filed June 22, 1938, now Patent No. 2,288,058, issued June 30, 1942, there is described a machine for practicing this process. In this process, a disc milling cutter of large diameter is used which has a plurality of cutting blades arranged part way only around its periphery with a gap between the first and last blades. The blades are made'with sidecutting edges of uniform circular arcuate profile shape, but the centers of curvature of cor-,

tooth space to the other in such timed relation tooth slots by rotating the cutter in engagement only approximate the finished profile shape at any point along the length of the tooth space.

For jobbing Work, it is also common to rough straight beve1 gears with reciprocating planing of the gear blank in straight paths which converge at an angle corresponding to the angle of longitudinal, convergence of the sides of the tooth surfaces being cut The tools cut in adjacent tooth spaces of therblank and by indexing The tools are reciprocated across the face with the cutter rotation that different blades of the cutter cut at different points along the length of the tooth space during a revolution of the cutter. A tooth space is completed when the cutter has made one revolution, and the blank is: indexed when the gap in the cutter isabreast of the blank.

tion jobs where the number of gears'to be cut is such as to justify the use of thehighly specaland costly cutter required.

A primary object of the present inventionis to provide a method and machine for roughing straight bevel gears, with tooth spaces tapering in depth andwidth from end to end and having straight bottoms and profiles very closely approaching the finished tooth shapes required,

whichwill be fast and at the same time relativelybevel gears.

ing effective cutting contour.

A further object of the invention is to provide .a method for rough-cutting straight bevel gears in which both sides of a tooth space may be cut simultaneously with a single disc milling cutter and with tooth shapes very closely approximating the-finished tooth shapes required.

A further object of the invention is to provide a process for cutting straight bevel' gears wherein the principles underlying the method of my prior application No. 181,177may be used but in which a cheaper cutter may be employed and the method used will have greater flexibility so that a single cutter may be employed economically in the cutting of various sizes and types of straight A' further object of the invention is to provide a very simple form of machine for cutting straight bevel gearswith a milling cutter in which a single'rotarymotion may be employed both to revolve the cutter and feed it-lengthwise of the tooth slot being cut so as to having a straight bottom.

Other objects of the invention will be apparent I hereinafter from the specification and fromthe recital of the appended claims.

With the present invention. a. disc milling produce a tooth slot I with the cutter spindle rotation. This iiirmtimt motion may be effected by a relative depthwise movement of the work, but in the preferred form of cutting machine is effected by movement of the cutter itself. It is produced without separate cams by mounting the cutter spindle in a slide and providing means that is connected to the cutter to constrain the slide to move inwardly and outwardly with the rotation of the cutter spindle. Thus as the cutter spindle rotates, the cutter center itself is constrained to movein a straight line parallel to the root line of the tooth space being out. In the preferred form of machine, the depth of the tooth space is controlled by av feed cam which is driven in time with the cutter spindle so that the cutter spindle makes an integral plural number of revolutions and the cutter makes a plurality of passages back and forth across the face of the blank in one revolution of the feed cam. The feed cam 'is so constructed as to effect a relatively slow 'depthwise feed movement of the slide in which the cutter spindle is journaled, during the cutting of a tooth space, andwhen the tooth space cutter is used that has a plurality of radially disposed cutting blades arranged completely around its periphery. These blades are preferably of circular arcuate profile shape and corresponding side-cutting edges of the blades are preferably made of the same curvature but the centers of curvature of successive corresponding side-cutting edges are displaced from one another so that successive corresponding side-cutting edges have progressively different inclinations to a-plane of rotation perpendicular to the axis of the cutter and the cutter has a progressively varya tooth space of a gear, the cutter is rotated in engagement with the gear-blank while being fed back and forth across the face of the blank from one end of the tooth space to the other and while being simultaneously fed into depth. The rotation of the cutter is so timed to the lengthwise In the cutting of feed movement that during arevolution of the cutter each blade cuts at one specific point only, lengthwise of the tooth. In the preferred embodiment, the cutter makes one revolution for a complete back ahd forth movement along the length of. a tooth space. The cutter, however, makes several passages back and forth across the face of the blank during the cutting of a single tooth space, being -fed allthe while into depth so that on successive passages it cuts deeper and deeper into the tooth space until full depth is reached. Then the cutter is withdrawn from engagement with the blank and the blank is indexed.

One of the novel features of the invention is the arrangement' whereby a single rotary motion is employed to produce both'the rotation of the cutter and its'feed motion back andforth across the face of the blank. To this end thecutter is mounted on the cutter spindle of the .machine, eccentrically of the axis of rotation of that spindle, and the resulting eccentric motion spindle revolves. is adjustable to adjust the length of cutter stroke.

To cut a tooth space with a straight bottom, the work'must be movedrelatively toward and from the cutter during the cutter spindle rotation, and this motion must be a harmonic motion in time I of the cutter causes the cutter to travel back and forth across the face of the blank as the cutter The eccentricity of the cuttef has been cut to full depth, the cam permits withdrawal of the slide and cutter through operation of a spring so that the gear blank may be indexed.

In the drawings:

Figs. 1 to 5 inclusive are diagrammatic views,

illustrating the principles underlying the process of thepresent invention;

Fig. 6 is a diagrammatic view, illustrating the preferred construction of a cutter used for mac:

ticing the present invention, and showin three \diflerent blades of, this cutter superimposed on one another;

. 2 I Fig. 7 is a perspective view of a machine built according to a present preferred embodiment of the invention;

Fig. 8 is a vertical sectional view through the cutter end of this machine;

Fig. 9 is a part plan, part horizontal sectionalview of the parts shown in Fig. 8;

Fig. 10 is a fragmentary sectional view on the line Ill-l0 ofFig.8;

Fig. 11 is a fragmentary sectional view on the line H-H of Fig. 8;

Fig. 12 is a sectional view on the line I2l2 of Fig. 9;

t-Flg. 13 is a view looking at the rearend of the work head of the machine, parts being broken gear out according to the present invention with crowned teeth for localization of tooth bear-iiig.

As already stated, the cutter used in the pres ent invention is preferably provided with-cutting blades whose side-cutting edges are of concave circular arcuate profile shape but the centers of curvature of the successive corresponding profiles are displaced fromv one another axially and re.- diallyof the cutter axis. This construction is illustrated diagrammatically in Fig. 6. Here the r are shown in full lines.

edges of the blade, which is intended to operate denoted at and 20', respectively. Opposite side cutting edges of the blade, which is intended to operate at a point midway the length of a tooth space, are denoted at 2| and 2|, respectively, and

Opposite side cutting.

at the large end of the tooth space, are shown in dotted lines and are denoted at 22 and 22', respectively. Ordinarily the cutting surfaces on the two sides are made symmetrical with reference to a median plane 23 perpendicular to the axis of the cutter.

Corresponding side-cutting edges 20, 2 l, 22, etc. of the blades have the same radii r of curvature, and likewise the corresponding opposite side-cutting edges 20', 2|, 22, etc. have the same radii of curvature. The centers of curvature of corresponding side-cutting edges of successive blades are, however, displaced fromone another. Thus the center of curvature of the side-cutting edge 23 may be at 24 on theline 21, the center of curvature of the side-cutting edge 24 may be at 25, and the center of curvature of the side-cutting edge 22 may be at 26. The centers of curvature of successive corresponding side-cutting edges may be displaced from one another at a varying rate. The blades are preferably all made of the same height, as shown in Fig. 6, but they may be made of progressively varying height,

In cutting a gear with the process of this invention, the cutter. C is mounted so that its center -y is offset from the turning center a: of the cutter, that is, from the axisof the cutter spindle, and the amount of offset is equal to one'half of the desired lengthwise feed movement of the cutter,

which amount is, of course, determinedby thewidth of face .of the gear to be cut. During cutting, then,'the center 1/ of the cutter describes a circle E about the turning center so.

In Figs. 1 to 5 inclusive, the gear blank that is to be roughed, is designated at B. Its axis is denoted at A and its apex at P. The gear blank is, of course. adjusted to its root angle R. (Fig. 3)

and is also adjusted in the direction of the arrows 28 and 29 in accordance with the mean cone distance of the work and the desired depth of tooth to be cut. In Figs. 1 to 5 inclusive, it is assumed that the depthwise feed movement for producing the depth of tooth space is imparted to the work and that the harmoni-cmotion for producing a, straight tooth surface bottom is also imparted'to the work, l

, Fig. lshows the start of the roughing cut. Fig. 2 shows a phase of the roughing operation before full depth is reached. Fig. 3 shows the cutter at 'full depth position with the out being taken at the small end of the tooth space; Fig. 4 showsthe Fig. 2, its peripheral cutting surface 3| will first be moved inwardly towards the blank and then outwardly away from the blank. Likewise, as the cutter rotates about the axis a: from the position shown in Fig. 2 back to the position shown in Fig.

1, its peripheral surface 8| will first move furthe'r outwardly away from the blank and will then be moved inwardly again. If the axis a: is fixed, then, this means that the work must have a. movement awayfrom the axis a: as the cutter moves inwardly and towards the axis a: as the cutter moves outwardly if a straight tooth space bottom is to be cut in the blank. r A

The necessity for and character of this relative harmonic motion is illustarted quite clearly in Figs. 3 to 5 which illustrate what takes place when the cutter is cutting at full depth. In the position shown in Fig. 3, the peripheral surface 3| of the cutter is tangent to the root line 30 at the'small end of the tooth space. As the cutter revolves about the axis a: from the position shown in Fig, 3

- to the position shown in Fig. 4, the cutter center y moves through an angle of 90 on the circle E circumscribed about the axis 1:. This causes the periphery of the cutter to move inwardly toward the blank. To maintain the root line 30 of the tooth space tangent to the peripheral surface As the cutter revolves about the fixed center a:

from the position shown inFig. 4 to that shown in Fig. .5, the cutter moves away from the work again and to maintain the root line 30 of the work in tangency-with the periphery 3| of the cutter, and

cause the cutter to out further along the length of the tooth space, the work is moved inwardly again to the position shown in Fig. 5 which is the same position that, the work occupies in Fig. 3.

Ordinarily after the cutter has made one passage across the face of the blank at full depth position, the work will be withdrawn from engagement with the cutter and indexed. During feed into full depth position, however, the cutter will make several passages back and forth across the face of the blank, revolving continuously in the same direction and cutting on both-its forward and return passages, across the face. of the blank. On each return passage, the cutter climbcutter at full depth position with the out being taken at a point midway the length of the tooth space; and Fig. 5 shows the cutter at full depth position with the out being taken at the large' end of the tooth space,- The peripheral cutting surface of the cutter is denoted at 3|. The cutter is assumed to be rotating in the direction of the arrow 32 throughout the whole of the cutting operation.

In Figs. 1 to 5, it will be seen that as the cutter revolves about the axis a: from a position such as shown in Fig. 1 to a position such as shown in cause the cutter to cut back along the length of' cuts.

To understand the complete cycle of operation,

then, it will be assumed that the cutter continues to cut as it revolves from the angular position shown in Fig. 5,back to the the angular position' shown in Fig. 3. .Such a cut might actually be employed were it desired to obtain a fine finish.

' During the first of its rotation from the position shown in Fig. 5, the cutter will continue to.

move away fromthe work. To maintain the root surface 30 of the tooth space in tangency to the peripheral surface 3| of the cutter-and the tooth space toward the small end thereof during this part of the cutter rotation, the work must be moved further into the cutter. Finally, as the rotation about the axis :2: causes the cutter to return to the position shown in Fig. 3, the cute ter moves toward the work again. To maintain tangen'cy between the root line of the-blank and I the periphery of the cutter during thispart of the cutter-rotation and .to cause the cutter to cut on to the small'end of the tooth space, the blank isagairi fed away from the cutter.

, The described motion of first outward and then in'wardmo've'ment of the work relative to the cutter'takes" place On each revolution of the cutter as the cutter is being fed into full depth position.

It is a harmonic motion at the rate of once per revolution of the cutter. This harmonic motion causes the cutter to cut a straight tooth bottom in the blank. The depth feed required to cut the desired depth of the tooth space is added to this harmonic motion until full depth position is reached. This depth feed may also be in the direction of the arrow 29. The depth feed ceases when full depth position is reached, but the harmonic motion goes on until the cutter has swept the full length of the tooth space from the position shown in Fig. 3 to the position shown in As already stated, the cutter spindle 45 is jour- Fig. 5. The depth feed may then be reversed and the work be moved clear of the cutter and indexed.

This may be done during the half revolution of the cutter'which takes place between the position of the cutter shown in Fig. 5 and the position of the cutter shown in Fig. 1. Then the cycle begins anew. 1

In the machine which is illustrated in the drawings for practicing the invention, the harmonic motion is imparted to the cutter instead of to the Work and the cutter spindle is not fixed but is mounted in a slide that is reciprocable toward and from the work. The harmonic motion is imparted tothis slide. The depthwise feed-movement is also i mparted.to the cutter and slide.

Reference will now be had to Figs. 7 to 19 inclusive for a description of this'machine.

40 denotes the base or frame of the machine. The base is formed on its upper face with parallel longitudinal ways 4| and 42 (Figs. '7 and 11) and with parallel longitudinal ways 43 and 44 (Fig. [1). The slide 45 (Figs. 7, 8, 9, and 11) is mounted to reciprocate on the way 4| and 42. The cutter spindle 48 (Fig. 8) is journaled in this slide.

naled in the slide 45. This slide is held on the ways 4| and 42 simply by its own weight. It is prevented from lifting oil. of the ways 4| and 42 by washers 50 (Fig. 11). These washers are mounted on screws 6| that thread into the base 40 of the machine and they are held by spacer sleeves 52 so that their under faces just clear the tops of the recesses 53 in the slide 45 in which the heads of the screws 5| lie.

The cutterspindle 45 is provided at its upper end with an enlarged head 55. The periphery of this head may be concentric of the axis a: of the cutter spindle, but in order to get as large a head-as possible without having undue overhang of the cutter, the periphery of this head 55 is preferably made eccentric of the axis a: of the cutter spindle, as shown. .There is a plate 55 keyed to the enlarged head 55 of the spindle 45 by an elongated key that fits in the slot 58 formed in the upper face of the head 55 (Figs. 8 and 10). The plate 85 is formed with a nose portion 59 which is adapted to enter the bore of the cutter C which is to be used on the machine.

The cutter shown is a disc milling gutter of the inserted blade type and has 2. pl rality of radially disposed cutting blades H arrai l ged completely around its periphery. Each blad may be formed with two opposite side-cutting edges, but

preferably'each blade-is formed with a single side-- cutting edge and alternate blades are provided with opposite side-cutting edges. The blades are 2,246,503, issued June 24, 1941.. The blades are Mounted on the" ways 43 and 44 for adjustment toward and away from the cutter is a slide 50 (Fig. 7). Mounted on the slide 50 is a plate 5|. 'Mounted on the plate 5| is the work head 52. The work spindle 53 is journaled in the work.

head 52.

The slide 50 has an inclined upper face as shown clearly inFig. 7. This face slants downwardly toward-- the cutter end of the machine. The plate 5| has a complementarily inclined lower face. The plate 5| is adjustably mounted on the slide 50 for adjustment in two directions at right angles to one another. By adjustment of the plate toward and from the cutter end of the machine, the heightof the work spindle can be raised or lowered. This adjustment is provided to permit of control of the tooth profile shapes of the gears being cut and to permit of cuttingstraight tooth bypoid gears. The adjustment of the plate 5| laterally of the slide 50 is for the purpose of 'adjusting the work in accordance with the mean cone distance of the gearto be cut. Both adjustments are effected manually, and after adjustment, the plate 5| is secured to the slide 50 by T- bolts 55. These bolts pass through elongated'slots 58 in the plate 5| and theirheads engage in the transverse T-slots 51 formed in the'upper face of the slide 50. The slots 55 extend at right angles to the slots 51.

vThe work head 52 is mounted on the plate 5| for angular adjustment about an axis that extends at right angles,to and intersects the axis of the work spindle. This adjustment is for the purpose relieved on their sides'and tips back of their front faces and may be relieved by any suitable relieving process such as, for instance, the process described in the U. S. patent to Leonard O. Carlsen, No.

secured to the cutter head Ill by screws 12.

The plate 58 is mounted on the head 85 for lateral adjustment relative thereto to adjust the eccentricity .of the cutter. For the purposes of effecting this lateral adjustment, there are two adjusting screws 14 and I S'threaded-into the plate 58 to engage the periphery of the head 55 To permit at diametrically opposed points. eflecting this adjustment accurately, there is a graduated scale 8| (Fig. 10) secured to one of 1 the'screws i5. This scale is adapted to slide in a slot 52 formed therefor in theupper face of the plate 58 and is adapted to be read against a zero mark inscribed on the upper face of the plate 55.

The plate 55 is adjustment, by screws 15 which pass through elongated slots 19 formed in both the plate 55 l and the head 15 of the cutter and which thread into the head 55. The cutter is secured tothe plate 58 by these screws 15 and by the clamping disc 11 and bolt 18.

The plate 55 is journaled by means of the needle bearings in a yoke-member or'arm 83. The rear end of this arm is formed with aconvexly curvedcontact portion or face 89. This contact face 89 engages the front face of a hardened block or abutment 90 (Figs. 8 and 9) that is securedby screws 9| to a lever arm 92. I The lever arm 92 is pivotally mounted by means of the pin 93 in the frame of the machine.

Adjustably mounted on the rear face of the lever arm 92 is a block 85. This block is adsecured to the head as, after justed on the lever arm 92 radially of the pivot 93 by means .of a screw v99. This screw is jour- I99 formed in the rear face of the lever arm 92.

There is a contact block I92 secured to the block 95 by means of a screw I93. This block has a convex rear face and engages ahardened plate I94 that is fastened in any suitable manner to lever arm I95. This lever arm is pivotally mounted in the frame of the machine by means of a. pin I96. V

Journaled on a pin I98, that is mounted in the lever .I95, is a rotatable roller I91. This roller is adapted to engage and ride on the periphery of the cam H9. The 'cam Die the feed cam of the machine and controls the depth of the tooth slots which are to be cut in a given gear blank. The cam shown is so formed as to make one revolution for each tooth slot which is to be cut, and, during a revolution, the cam feeds the cutterinto the gear blank. being out until full depth position is reached and then permits withdrawal of the cutter from engagement with the blank so as to allow indexing ofthe blank.

The motion produced by the cam H9 is transmitted to the tool slide 45 and cutter C through the lever I95,- plate I94, contact block I92, plate 95, lever 92, contact-block 99, arm 83, bearings 99, head 86, screws 14 and 15, head 65, and spindie 49. The roller I98 is held in engagement with the cam I I9,.'the hardened block I92 is held in engagement with the hardened plate I94, and the convex end face 89 of the arm 83 is held in engagement with the hardened-plate 99 by a lever H and a coil spring H6.

The lever H5 is pivoted by means of the pin II! in the base or frame of the machine. It is bifurcated at one end and is formed with ears H8 and H9 that engage around pins 81 and 88 nected by means of the pin I29 with the head I2I of a plunger I22. This plunger is mounted in a sleeve I23 that is secured bymeans of the nut I24 in the base or frame of the machine. The coil spring H9 is mounted to surround the plunger I22 and is interposed between the head I2l .of this plunger and a nipple I25 whch is mounted in.a recess in the sleeve I23 and-surrounds the plunger I22.

The feed cam II9 'rotates on a relatively fixed axis. At any instant in its rotation, then, the point of its contact with the roller I9! is; therefore, fixed. Hence as'the cutter spindle 49 re volves, the eccentrically disposed plate 69 causes the slide 45 to move back and forth on the ways 4!. and 42. This motion is in additionto and superimposed upon the depthwise displacement.

:1: again denotes the axis of the cutter spindle 46 which is journaled in the slide 45. 1/ again denotes the axis of the cutter itself which is secured to the. plate 66 that is rotatably mounted in the yoke-member or arm 83. This arm has, as described, a convex contact surface 89 at its inner end which engages with the front plane face of the hardened block or abutment 99 and the contact surface 89 is held against the block 99 by the coil spring 8.

As already pointed out, at any instant inthe operation of the machine, the block 99 is relatively fixed, and for the purpose of analyzing the eccentric motion of the cutter, the block 99 travels from the small end of the tooth space to a point midway the length thereof. In the further rotation of the cutter spindle fromthe position shown in Fig. 17 to that shown in Fig. 18,

the arm 83 is swung to the left, and the slide that are formed integral with the arm 83. At its opposite end, the lever H5 is pivotally con-- and cutter'spindle 46 move forwardly-again large end of the tooth. In the furthe rotation so that the cutter is moved on to cat at the of the cutter spindle from the position hown in Fig. 18 to that shown in Fig. 19, the cutter begins to movepback across the tooth face again,

but the slide 45 continues to move forward to its extreme forward positionshown in Fig. 19 and the arm 93 returns to central position again with the cutter again cutting on center at a point midway the length of the tooth space. In thefurther rotation of the cutter spindle from the position shown in Fig. 19 back to that shown in Fig. 16, the arm 83 is swung on to'the right,

causing the cutter to out towards thesmall end of the tooth space, and the slide 45 moves rearwardly again. Thus it will be seen that in a revolution of the cutter, the arm 83 has a pendular movement,-swinging from left to right and backagain, and the ,slide'45 has a harmonic reciprocatary movement moving rearwardly and then forwardly and then rearwardly again.

Further, it will be seen that during these movements of the arm 83 and slide 45, the center 1! of the cutter will travel in-a path parallel to the front face of. the block 99 and parallel to the root line of the tooth space being cut.

Of course, during the cycle of cutting a tooth space, the block 99 is advanced by the operation of the feed cam I I9 through the levers I; and 92 and their connecting parts. Thus, during its back and forth travel across the face of the blank, the cutter is fedinto the tooth space to cut the tooth space to the full depth. When full depth position is reached, the roller I91 moves downoif of the high part of the cam H9 on to the lowest part thereof again and the spring Mt operates to withdraw the cutter from engagement with the blank to permit of indexing the blank. In roughing, the cutter is preferably passed only once across the face of the blank at full depth position, simply moving from the small to the large end of the tooth during half a revolution of the cutter spindle. Then the cutter is withdrawn and the blank indexed durdiate its ends.

ing the other half revolution of the cutter spindle.

The cutter spindle 46 is driven from the motor I35 (Fig.15). The armature shaft I36 of this motor is coupled through a suitable coupling I31 to a bevel pinion I38 (Figs. 15 and 12). The

is keyed to a shaft I48. The shaft I48 is suitably journaled in the base of the machine. It has a spur gear I fastened to its outer end and this spur gear meshes with a spur gear I42 which issecured to a shaft I43. The shaft I43 is suitably journaled in the base of the machine. It has a bevel pinion I44 mounted on it interme- This bevel pinion meshes with a bevel gear I45 (Figs. 8 and 15). The bevel gear I45 is keyed to a shaft I46 that has a sliding splined connection, with a spur pinion I41.

The pinion I41 is suitably journaled in slide 45 and meshes with a spur gear I48 that is keyed to a shaft I49. The shaft I49 is suitably journaled in the same slide 45 and has integral with "pinion I38 meshes with a bevel gear I39 which which engages with the tail of the pawl. The

pawl is held out of engagement with the ratchet wheel, during cutting, by means of a dog I84. This dog is, pivotally mounted in the work head 52 by means of the pin I85. The dog is adapted to engage 9. lug I86 that is formedon the pawl;

The dog I84 serves, also, to prevent rotation of the stop plate I18 in one direction, for it is adapted to engage a shoulder formed on the periphery of the stop plate. Rotation of the stop plate in the opposite direction is prevented by means of a second dog I88. This second it a bevel pinion, 158. The bevel pinion I58 meshes with the bevelgear I5I which is keyed to the cutter spindle 46. I

The feed cam H8 is driven in time with the spindle makes an integral number of revolutions during a cycle of operation of the machine. The drive to the feed cam H8 is from the shaft I43.

, This shaft has a spur gear I55 (Figs. 12 and 15) keyed to one end. This spur gear I55 forms one of a set of change gears of which the other members are denoted at I56, I51, and I58, respectively. Gears I56 and I51 are mounted on a stud or post forming part of a, standard quadrant. The gear I56 meshes with the pinion I55 and the gear I51 meshes with the gear I58. The

gear I 58 is secured to shaft I68 which is suitably journaled in the base or frame of the machine. The shaft I68 has a worm I6I formed integral with it (Figs. 8, 12, and 15). The worm I 6I meshes with a wormwheel I62 which is keyed to a vertical shaft I63. The vertical shaft I63 is suitably journaled in the base of the machine. The feed cam I I8 is keyed to the upper end of this shaft I63. It seats against a shoulder on the shaft and is held against axial movement relative to the shaft by the nut I64.

In the machine illustrated in the drawings, a universal or worm and wormwheel type index mechanism is provided. This index mechanism is driven from a separate motor I18 (Figs. 14

I rotation of the cutter spindle so that the cutter pawl out of engagement with the ratchet wheel, by means of the sprin pressed plungers I89 and I98, respectively. The dog I84 is moved out of operative position against the resistance of the spring pressed plunger I89 by a rod I82 which is pivotally connected at I93 to the dog I84 and which is integral with the plunger I94 of the solenoid I95.

The solenoid is operated periodically'byv the closing of a normally open switch I96 (Figs. 8 and 15) which is suitably mounted in the base of the machine. This switch is operated by a cam I91 that is secured in any suitable fashion to a plate I98 which is keyed to the same'shaft I63 on which the feed cam II8 of the machine is mounted. Thus the switch I96 may be closed in time with the rotation of the feed cam so that when the cutter is withdrawn from the work at the end of the cutting of a tooth space-of the gear blank, the switch I96 is closed to actuate the solenoid I95 to withdraw the dog I84 from operative position and allow the pawl I8I to enage the ratchet wheel I15 under actuation of the spring-pressed plunger I82,'permitting motion to be transmitted fromthe motor I18, to the stop plate I18-wand shaft I11. When the switch I96 is closed, the circuit is made to'the solenoid I 85 through the lines I99 and I88 (Fig. 15). A

There is a spur pinion 288 (Figs. 13 and 15) fastened to the upper end of the shaft I11. This ,SDlll pinion forms one of 'a set of index change and 15) which is mounted in the work head 52.

During actual cutting of a. tooth space, the work spindle is held stationary on its axis and is rotated only for indexing. Keyed to the armature shaft "I of the motor I18 is a-worm I12.

This worm meshes with a wormwheel I13 (Figs.

13, 14,'and 15) which is keyed to the sleeve portion I14 of a ratchet wheel I15. The ratchet wheel I15 and its sleeve I14 are journaled by means of the bushing I15 on a shaft I11; Keyed to the shaft I11 is a stop-plate I18. This stop plate surrounds the ratchet wheel I 15 and is coaxial therewith. It is provided with a circumferential slot I19 within which is pivoted by means of the pin I 88, a pawl I8I. The pawl isadapted to be engaged periodically with the ratchet wheel I15 to transmit the motion of the motor I18 tothe stop plate I18 and' the shaft I11 dexing of the work spindle.

The pawl I 8| is-urged constantly toward opto effect in- .erative position by a: spring-pressed plunger I82 which is housed inthe stop plate I18 and gears of which the other members are denoted at MI, 282, and 283. The gears 28I and 282 are mounted on a stub shaft forming part of a quadrant of usual construction. The gear 28I meshes with the pinion 288 and the gear 282 meshes with the gear 283. Gear 283 is keyed to a shaft 285 which is suitably journaled in the work head 52.

There is a worm 286 integral with the shaft 285,

and this worm meshes with a wormwheel 281' l I which is keyed to the work spindle 53. Thus when the pawl I8I is in engagement with the ratchetwheel I15, rotation is transmitted from the motor I12 to the work spindle 53 to index the work spindle through an angular distance determined by the index change gears 288, 28],

282, and 283. The cam I91 holds the switch I96 closed only for an instant and then allows the switch to open again so that when the stop plate I16 has made one revolution, the dog I84 is re-' turned into'engagement with the stop plate and with the ledge portion I86 of the pawl I8I to withdraw the pawl from engagement with the I88 are normally ratchet wheel, and the indexing cycle is complete. I

The plate I98 (Fig. 8) carries a cam 2") which operates the automatic stop 'mechanismcf the machine. This may be in the form of an automatic stop 2| I of any suitable construction. This stop mechanism is advanced once for each tooth space to be cut and; when all of the tooth spaces of the blank have been cut, operates to stop the motors I35 and I10, stopping the machine. The

completed gear blank may then be removed from the machine and anew blank chucked.

The chucking mechanism may be of any suitable construction and forms no partof the present invention. The work head may be withdrawn from operative position for removal of the completed work piece or chucking of a new blank, and returned to operative position again, by hydraulically operated mechanism. The movements of the work head to and from-chucking position, the clamping of the work head in operative posi tion and thechucking of the gear blank may also be hydraulically controlled. These several hydraulically actuated mechanisms may be operated from a single valve controlled by a hand lever 2I5 (Fig. '7) in known manner. Any other suitable construction may, however, be employed.

The operation of'the machine will readily be understood from the preceding description but may be briefly summed up here. First of all, of course, the work is adjusted for root angle, cone distance, and height position by adjustment of the work head 52, on the plate 5| and of the plate 5| on the slide 50. The depth feed of the cutter slide 45 is adjusted by adjustment of the block 95 (Fig. 9) on the lever 92, and the eccentricity orthe cutteris adjusted by adjustment of the plate on the head 65 of tool spindle 46. The work is then chucked and brought into operative relation with the cutter. Then the machine may be started. The work spindle is held stationary during cutting by engagementof the lock dogs I84 and I88 with the stop plate I18, the pawl I8I' being held out of engagement with the ratchet wheel I by the dog I 84. During operation of the machine, the cutter spindle 45 rotates con-- tinuously being driven from the motor I through the gearing I38, I39, I4I, I42, I44, I45,

I41, I48, I50, and I5I (Figs. 8, 12 and 15). .This

causes the cutter C to be rotated and to be moved back and forth across the face of the gear blank. Because the cutter is mounted eccentrically of the spindle 46 and because of the engagement of the arm 83 with the contact block 90, as the cutter spindle 46 rotates, aback and forth movement in a direction perpendicular to the root line of the blank is imparted to the slide 45 and to the cutter spindle. This causes the cutter to travel back and forth across the face of the gear blank as it rotates in engagement with the blank. Simultaneously the. cutter is fed into the blank, under actuation of,the rotating feed cam III] to cut a tooth space to proper depth. The cutter makes several revolutions and several passages back and forth across the face of the blank while it is being fed into depth, the number of passages being controlled by the feed cam. The feed cam is, of course, rotated in time with the rotation of the cutter spindle through the gearing I55, I56, I51, I58, NH; and I62 (Figs. 8,"

12, and 15). When the tooth space has been cut ,tofull depth, the feed cam 'allows a quick withdrawal of the cutter away from the gear blank through operation of the spring IIB as the roller I01 rides down off of the high spot of the cam into engagement with the ratchet wheel I15 and causes the work spindle 53 to be indexed through operation of the gearing I12, I13, the pawl IN and ratchet wheel I15, shaft I11, gearing 200, 211i, 202, 203, 206, and 201 (Figs. 13, 14, and 15). During indexing, the lock'dog I88 ratchets idly over the periphery of the stop-plate I18. When the indexing has been completed, the work spindle 53 is again locked against rotation by return of the stop dog I84 into engagement with the pawl IBI and stop plate I18 under actuation of the spring pressed plunger I89. The cam I I0 operates-then, to feed the cutter back into engagement with the gear blank and the cycle begins anew to cut a new tooth space of the gear passed back and forth across the face of the blank until a tooth space is cut, and then being withdrawn, and the blank.indexed. When all of the tooth spaces of the blank have been cut, the cam 2III (Figs. 8 and 15) operates to trip the automatic stop mechanism 2| I of the machine and the machine is stopped. Then the roughed gear may be taken off of the machine and a ne w blank chucked. I

While the invention has been described particularly in connection with a process and machine for rough-cutting gears, it will be understood that this same process and machine may be employed for finish cutting, if desired. In this case, the blades of the cutter must be relieved quite accurately. This may be done by the process of relieving blades of Revacycle cutters.

In the machine described, it will be seen that adjustment of the block (Fig. 9) on lever 512 varies'the amount of the depth feed transmitted from the cam III] to the feed lever 82, and that adjustment of the plate '66 with reference to the spindle 46. Both the depth feed and the relative fed lengthwise of the teeth of the gear blank are therefore independently adjustable. This makes for great flexibility and is particularly valuable for Jobbing work.

Now while the invention has been described in connection with use of a cutter that has blades of progressively different effective cutting action, it is to be understood that conventional milling cutters may also be used on the machine at reduced advantage, but still at an advantage as compared with bevel gear roughing machines of the prior art which employ conventional disc milling cutters. The advantage lies in the use of large cutters which take long sweeping cuts and in a combination in effect of depth feed and lengthwise feedso that long runouts are avoided plate is used, the .center of the cutter does not move exactly in a straight line lengthwise of a method of this invention. a are denoted at 236. As will be seen, opposite side tooth: surfaces 228 and 238 of the teeth are 'longiv50 tooth space but approaches a little closer to the work at both ends of the relative-lengthwise feed movement. In other words, it is possible with such a plate to cut a little deeper at the tooth ends and thereby reduce the length of tooth bear- .ing. In this way, it is possible to obtain a localized tooth bearing on the gear being cut so that when the gear is run with its mate, the pair may accommodate themselves readily tothe variations in tooth loads and mountings that a concave path such as denoted at 223,'the concavity of this path depending, of course, upon the concavity of the control surface. 224 denotes a position of thecutter center when the cutter is cutting at the small end of the tooth; 224' denotes the position of the cutter center when the cutter g;

is cutting at the center of the tooth, and 224" denotes the position of the cutter center when the cutter is cutting at the large end ,of the tooth. 225 and 226 denote the outside and inside circles,

respectively, of the cutting blades when the cutter :m

center is at the mean position 224'. In this positiornthe mean point of contact between the cutter and the side th surface 228 of the gear is at 221, while 229 s a line of contact between cutter and tooth surface for this mean position. It will :15

be noted that, as already indicated, the line of contact 229 is inclined at an angle I of more than to the radius 230 of. thecutter at the mean contact point 221. 232 isthe point of tangency' between the outside circle 225 of the cutter and the root line 233 of the blank. When the cutter center is moved in acurved path 223, as described, the bottom of the tooth space will be convex, as

denoted at 235, unless the blades of the cutter are varied in height to compensate for this condition. 45

Fig. 21 shows on a somewhat enlarged scale a ear out to have crowned teeth according to the The teeth of the gear tudinal ly crowned.- When such a gear is meshed with alnate cut it the same way .or with a mate out without crowning, it will mesh with theinate with a localized tooth hearing.

In general it may be said that while the'invention has been described in connection with a particular embodiment thereof, it will be understood that it is capable of further modification and use and that this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in .the gear art and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

Having thus described my invention, what I claim is: 1. The method of producing a gear which comprises cutting each tooth space-of the gear with a rotary disc milling cutter, that has a plurality of radially disposed cutting blades, by rotating said cutter about an eccentric axis while producing a relative reciprocatory movement between. 7 5

To produce a localized tooth bearl.

the cutter and the work in the direction of tooth depth in time with the cutter rotation and of a harmonic nature so that the cutter will move back and forth across the face of the work during a revolution, and periodically indexing the blank. 2. The method of producing a gear which comprises cutting each tooth space of the gear with a rotary disc milling cutter, that has a plurality of radially disposed cutting blades, whose corresponding side-cutting. edges have different effective profile shapes, by rotating said cutter about an eccentric axis while producing a relative reciprocatory movement between the cutter and the work in the direction of tooth depth in time with the cutter rotating and of a harmonic nature so that the cutter will move back and forth across the face of the blank during a revolution, and effecting a relative depthwise I feed movement between the cutter and blank to cut the tooth space to full depth, and then eilecting a relative withdrawal movement between the cutter and blank, and indexing the blank.

3-. The method of cutting a gear which comprises cutting each tooth space with a rotary disc milling cutter, thathas a plurality of radially disposed cutting blades whose corresponding sidecutting edges are of the same circular arcuate profile shape but whose successive corresponding side-cutting edges are differently inclined to a plane of rotation perpendicular to the axis of the cutter, by rotating said cutter in engagement with a gear blank while. effecting a relative recipro catory motion of a harmonic nature between the work and the cutter in time with the cutter rotation in a direction perpendicular to the root line of the tooth space'so that the center of the cutter travels back and forth in the direction of said root line during a revolution of the cutter, and periodically indexing the blank.

4. The method of cutting a straight tooth tapered gear which comprises cutting each tooth space with a rotary disc cutter that has a plurality of cutting blades disposed radially of a common axis whose corresponding side-cutting edges are of the same circular arcuate profile shape but whose successive corresponding side cutting edges are differently inclined to a plane Y of rotation perpendicular to the axis of the cutter, by rotating said cutter in engagement with a gear blank about an axis eccentric to said common axis while effecting a relative reciprocatory movement ofa harmonic nature between the cutter and the work in time with the cutter rotation and in a direction perpendicular to the root line of the work, and periodicallyindexing the blank.

5. The method of cutting a straight tooth tapered gear which comprises cutting each tooth space of the gear with a rotary, disc cutter that has a plurality of radially disposed cutting. blades whose corresponding side cutting edges are of the same circular arcuate profile shape but whose successive corresponding side-cutting edges are differently inclined to a plane of rotationperpendicular to the axis of the cutter, by rotating said cutter on an eccentric axiswhile causing the'center of the cutter, during rotation of the cutter, to reciprocate back and forth in a line parallel to the root line of the tooth space being cut at the rate of a reciprocation perrevolution of the cutter, and effecting a relative depthwise feed movement between the c'ugker and" blank, and periodically indexing the bla a 6. In ,a machine for producing gears, a work spindle, a tool spindle, a slide on which one of said spindles is mounted, a supp rt on which the slide is mounted for reciprocation in a direction at right angles to the axis of the tool spindle,

the cutter rotation so that the cutter makes a plurality of revolutions during a cycle of feed and withdrawal, and means. for periodically indexing the work spindle.

12. In a machine for producing gears, a work spindle, a tool spindle, a rotary disc cutter having a plurality 'of radially disposed cutting blades whose corresponding side-cutting edges are of the same arcuate profile shape but whose successive corresponding side-cutting edges are differently inclined to a plane of rotation perpendicular to the axis of the cutter, secured to said tool cutter secured to said tool spindle with its center eccentric of the axis of saidspindle, means for rotating the tool spindle, means for imparting to said slide a harmonic movement back and forth in a direction perpendicular to the root line of a tooth space of the gear in time with the cutter rotation during a revolution of the tool spindle, means for simultaneously imparting to said slide a movement of feed in the described direction and for periodically withdrawing said slide from cutting position, and means for periodically indexing the work spindle.

8. In a machine for producing gears, a work spindle, a tool spindle, a slide on which one of said spindles is journaled, a rotary disc milling cutter secured to said tool spindle with its center eccentric of the axis of said spindle, means lot spindle, l means for rotating the tool spindle, means for moving the tool spindle back and forth in time with the cutter rotation to pass the cutter back and forth across the face of the work, means for effecting a relative depthwise feed movement between the cutter and work to cut a tooth space of the work to full depth and for then withdrawing the cutter from engagement with the work, means for driving the last namedmeans in time with the rotation of the cutter rotating the tool spindle to rotate the cutter,

means responsive to the rotation of the cutter for efl'ecting reciprocation of said slide in time with the cutter rotation and at the rate of a reciprocation per re olution of the tool spindle, and means for periodically indexing the work spindle.

9. In a machine for producing gears, av work spindle, a tool spindle, a slide on which the tool spindle is Journaled, a plate secured to the tool spindle and having a peripheral surface eccentric of the axis of the tool spindle, a disc milling cutter secured to said plate. with its center eccentric of the axis of the tool spindle, a yoke member connected to said plate to oscillate on rotation of said plate, a relatively fixed abutment co-acting with said yoke member to reciprocate said slideon oscillation of said yoke member, means for rotating the cutter spindle, and means for periodically indexing the work spindle.

10. In a machine for producing gears, a work spindle, a tool spindle, a slide onwhich the tool spindle is journaled, a plate secured to the tool spindle and having a peripheral surface eccentric of the axis of the tool spindle, a disc milling cutter secured to said plate with its center eccentrio of the axis of the tool spindle, a yoke member connected to said plate to oscillate on rotation of said plate, a relatively fixed abutment co-acting with said yoke member to reciprocate said slide on oscillation of said yoke member, means,

into depth, means for rotating the cutter spindle, and means for periodically indexing the work spindle. r

11. In a machine for producing gears, a work spindle, a rotary disc milling cutter, means for rotating said cutter, means for, moving the cutter hack and forth across the'face of a gear blank in time with and once per cutter rotation, means for producing a relative feed movement'between the cutter and work to cut a tooth space of the gear to full depth and for then withdrawing the cutter from engagement with the work, means for driving the last named'means in time with spindle so that the cutter makes a plurality of revolutions during a cycle of feed and withdrawal, and means for periodically indexing the work.

13. In a machine for producing gears, a work spindle, a tool spindle, a rotary disc milling cutter secured to the tool spindle with its center eccentric of the axis of the tool spindle, a slide in which the tool spindle is journaled, a yoke mem-- ber secured to the cutter to oscillate on.r0tati0n of the tool spindle, a relatively fixed abutment,

co-acti ng with the yoke member to reciprocate the slide on oscillation of the yoke member, said abutment having a plane active face extending parallel to the root line ,of the tooth s e being cut, and means for rotating the'tool spindle, and means for periodically indexing the work spindle. i 1 14. In a machine for producing gears, a work spindle; a tool spindle, a rotary disc milling cut- .ter secured to the tool spindle with its'center eccentric of the axis of the tool spindle, a slide in which the tool spindle is journaled, a yoke member connected to the cutter to oscillate on rotation of the tool spindle, a relatively fixed abutment co-acting with the yoke member to reciprocate the slide on oscillation of the yoke member, said abutment having a plane active face parallel to the root line of the tooth space being out in the work, means fol-alternately advancing the abutment towards the work spindle to feed the cutter into depth and for periodical- 1y withdrawing the abutment through the amount of said advance, and means for'indexing the work spindle after withdrawal of the abutment.

15. The method of cutting a gear which comprises cutting each tooth space with a rotary disc milling cutter, that has a plurality of radially disposed cutting blades whose corresponding side cutting edges are of the same concave profile shape but whose successive corresponding side cutting edges are differently inclined to a plane of rotation perpendicular to the axis of the cutter, by rotating said'cutter in engagement with travels back and forth in the direction of said 

